Gypsum board that is used as wall board in the construction of buildings is made by depositing a water-based gypsum slurry onto a substrate, allowing the slurry to harden into panels, and then removing excess water from the panels by conveying the panels through a large industrial dryer. Likewise, wood veneer panels are conveyed through large industrial dryers to remove excess moisture from the veneer panels, prior to laminating the veneer panels together to form plywood.
Ordinarily, the industrial dryers used in the manufacturing of wallboard and plywood are lengthy, in some cases greater than fifty yards long. Because it would be somewhat impractical to make a single structure that is over fifty yards long, most dryers are usually assembled on site by connecting several hollow sub-assemblies end-to-end.
It happens that it is frequently necessary to access the interior of an industrial dryer to remove debris and to otherwise clean the interior. Accordingly, access doors are provided in the side walls of each subassembly, so that a person can open the door to a subassembly and enter and clean that particular subassembly. In existing dryers, each door is hinged about one of its vertical edges, to permit moving the door away from the wall of the dryer and thereby expose the interior of the associated subassembly.
The present invention recognizes that existing dryer doors have several drawbacks. One drawback is that because the hinge of each door must support the entire weight of the door when the door is open, the weight (and, hence, the size) of a subassembly door is limited. In turn, the size of the access opening through which a person can enter the subassembly is limited, effectively limiting the size of the subassembly itself. Indeed, in light of the requirement to avoid excessive pre-loading of the door hinges, the size of most dryer subassembly doors must be limited. Consequently, it is difficult and cumbersome to clean the interior of a subassembly, because it is difficult to maneuver cleaning equipment through the relatively confined access opening.
The present invention moreover recognizes that when the doors of adjacent subassemblies are both open, they can undesirably interfere with each other. For this reason, it may be difficult at best to clean two adjacent subassemblies at once. This is undesirable because it is advantageous to minimize the maintenance period of the dryer and thereby maximize the operating period of the dryer. Additionally, when a dryer door is pivoted outwardly to its open position, it undesirably impedes not only adjacent dryer doors, but the walking space next to the dryer as well.
Accordingly, it is an object of the present invention to provide a door for a dryer subassembly that does not pivot on a vertical hinge. Another object of the present invention is to provide a door for a dryer subassembly that does not impede the opening of the doors of adjacent subassemblies. Yet another object of the present invention is to provide a door for a dryer subassembly that does not impede the walkway next to the dryer. Still another object of the present invention is to provide a door for a dryer subassembly which is easy to use and cost-effective.